Search Results (33)

A comprehensive review of the DMD-based optical lithography system has been conducted. The essence of the point-array with an oblique-scanning and stepping operation principle has been systematically analyzed, which will serve as the core driving force for its development and application. Similar to conventional lithography, the system development has been presented from the aspects of critical dimension (CD) resolution, overlay accuracy, and throughput. With the unique characterizations of the digital virtue mask, achievements are summarized from integrated circuit (IC) manufacturing to various micro-scale fabrication processes. Full article

Mask optimization is a critical technique for enhancing imaging performance in digital micromirror device (DMD)-based maskless lithography. Conventional algorithms, however, often suffer from slow convergence and limited adaptability, particularly when handling complex multi-feature mask patterns. To address these challenges, this study proposes a hybrid Genetic–Hippo Optimization (GA-HO) algorithm that integrates the global exploration capability of the Genetic Algorithm (GA) with the local exploitation efficiency of the Hippocampus Optimization (HO) Algorithm. The approach employs grayscale modulation for adaptive mask optimization and introduces a global–local cyclic search mechanism to balance exploration and exploitation throughout the optimization process. Simulation results demonstrate that the GA-HO hybrid algorithm achieves a more pronounced improvement in overall optimization performance compared with the standard GA. In complex multi-line mask optimization, the standard GA achieves approximately a 18% enhancement in optimization accuracy, whereas the GA-HO algorithm achieves around a 30% improvement. Moreover, the GA-HO algorithm exhibits a smoother convergence curve, greater stability, and superior robustness. The hybrid method effectively suppresses linewidth variations and corner distortions caused by optical proximity effects (OPE), maintaining high imaging fidelity and stable optimization outcomes even under challenging mask conditions. Overall, the proposed GA-HO framework demonstrates excellent efficiency, adaptability, and precision, providing a reliable and high-performance solution for DMD-based maskless lithography. This work offers a strong theoretical and algorithmic foundation for advancing high-resolution, high-efficiency, and low-cost micro/nanofabrication technologies, highlighting the potential of heuristic hybrid optimization strategies for practical lithography applications. Full article

Liver cancer is one of the most common and lethal malignant tumors worldwide, of which hepatocellular carcinoma (HCC) accounts for 80%. In the process of forming liver cancer, cancer cell metastasis is the only path. First, cancer cells need to adhere to the walls of capillaries, then penetrate blood vessels and enter liver tissue, resulting in liver cancer. Existing diagnostic methods for cancer cannot reveal and study this process, so we need to simulate the microenvironment in vitro and observe the metastasis mechanism of liver cancer cells based on this. This article describes the design and manufacture of a biomimetic capillary network to achieve this goal. By combining maskless laser direct writing with backside lithography, a biomimetic vascular network with a semi-circular cross-section was created that more closely resembles real capillaries. This article mainly studies the influence of topological structure on cell flow velocity, and simulates the flow velocity and pressure of cell solutions in vascular networks to investigate the differences between the biomimetic capillary network and the real situation, in order to further optimize and provide new ideas for the study of the liver cancer cell metastasis and the in vitro dynamic mechanism. Full article

Polymeric optical waveguides represent an essential component in photonic technology thanks to their ability to guide light through controlled structures, enabling applications in telecommunications, sensors, and integrated devices. With the development of new materials and increasingly versatile manufacturing methods, these structures are being integrated into various systems at a rapid pace, while their dimensions are constantly being reduced. This article explores the main fabrication methods for polymeric optical waveguides, such as traditional and maskless photolithography, laser ablation, hot embossing, nanoimprint lithography, the Mosquito method, inkjet printing, aerosol jet printing, and electrohydrodynamic (EHD) printing. The operating principle of each method, the equipment and materials used, and their advantages, limitations, and practical applications are evaluated, in addition to the propagation losses and characterization of the waveguides obtained with each method. Full article

Interference lithography (IL) offers high throughput, excellent uniformity, and maskless patterning capabilities. Compared to other methods, IL enables large-area, cost-effective fabrication of periodic structures with subwavelength resolution, which is particularly valuable for sensing applications, enabling the development of more sensitive, high-resolution, and reliable sensors. This review provides a comprehensive analysis of IL from the perspective of optical field control. We first introduce the principles of interference field formation and summarize key system architectures, including Mach–Zehnder and Lloyd’s mirror configurations, as well as advanced schemes such as multi-beam interference and multi-step exposure for complex pattern generation. We then examine how wavefront engineering, polarization modulation, and phase stabilization influence pattern morphology, contrast, and large-area uniformity. To address dynamic drifts caused by environmental perturbations, both passive vibration isolation and active fringe-locking techniques are discussed. For fringe-locking systems, we review methods for drift monitoring, control algorithms, and feedback implementation. These developments enhance the capability of IL systems to deliver nanoscale accuracy under dynamic conditions, which is essential for stable and high-performance sensing. Looking ahead, IL is evolving into a versatile platform for sensor-oriented nanofabrication. By integrating physical modeling, precision optics, and real-time control, IL provides a robust foundation for advancing next-generation sensing technologies with higher sensitivity, resolution, and reliability. Full article

Three-dimensional (3D) photolithography has found wide applications in microelectronics, optoelectronics, biomedicine, etc. Traditionally, it requires repetitive exposure and developing cycles. Meanwhile, a laser direct writing (LDW) system with a digital micromirror device (DMD) enables high-speed maskless lithography with programmable doses. In this paper, we propose a quasi-3D digitized photolithography via LDW with a DMD to remove multiple developing cycles from the process. This approach quantizes the dose of the 3D geometry and stores it in a grayscale image. And the entire dose distribution can be formed by overlapping the exposures with sliced binary dose maps from the above grayscale dose map. In the image slicing algorithm, a modified Golomb coding is introduced to make full use of the highest available exposure intensity. Both 1D multi-step patterns and diffractive optical devices (DOEs) have been fabricated to verify its feasibility. This type of digitized quasi-3D photolithography can be applied to fabricating DOEs, microlens arrays (MLAs), micro-refractive optical elements (μROEs), etc., and 3D molds for micro-embossing/nano-imprinting. Full article

Direct-writing submicron copper circuits on glass with laser precision—without lithography, vacuum deposition, or etching—represents a transformative step in next-generation microfabrication. We present a high-resolution, maskless method for metallizing glass using ultrashort pulse Bessel beam laser processing, followed by silver ion activation and electroless copper plating. The laser-modified glass surface hosts nanoscale chemical defects that promote the in situ reduction of Ag⁺ to metallic Ag⁰ upon exposure to AgNO₃ solution. These silver seeds act as robust catalytic and adhesion sites for subsequent copper growth. Using this approach, we demonstrate circuit traces as narrow as 0.7 µm, featuring excellent uniformity and adhesion. Compared to conventional redistribution-layer (RDL) and under-bump-metallization (UBM) techniques, this process eliminates multiple lithographic and vacuum-based steps, significantly reducing process complexity and production time. The method is scalable and adaptable for applications in transparent electronics, fan-out packaging, and high-density interconnects. Full article

Lithography is crucial to semiconductor manufacturing, enabling the production of smaller, more powerful electronic devices. This review explores the evolution, principles, and advancements of key lithography techniques, including extreme ultraviolet (EUV) lithography, electron beam lithography (EBL), X-ray lithography (XRL), ion beam lithography (IBL), and nanoimprint lithography (NIL). Each method is analyzed based on its working principles, resolution, resist materials, and applications. EUV lithography, with sub-10 nm resolution, is vital for extending Moore’s Law, leveraging high-NA optics and chemically amplified resists. EBL and IBL enable high-precision maskless patterning for prototyping but suffer from low throughput. XRL, using synchrotron radiation, achieves deep, high-resolution features, while NIL provides a cost-effective, high-throughput method for replicating nanostructures. Alignment marks play a key role in precise layer-to-layer registration, with innovations enhancing accuracy in advanced systems. The mask fabrication process is also examined, highlighting materials like molybdenum silicide for EUV and defect mitigation strategies such as automated inspection and repair. Despite challenges in resolution, defect control, and material innovation, lithography remains indispensable in semiconductor scaling, supporting applications in integrated circuits, photonics, and MEMS/NEMS devices. Various molecular strategies, mechanisms, and molecular dynamic simulations to overcome the fundamental lithographic limits are also highlighted in detail. This review offers insights into lithography’s present and future, aiding researchers in nanoscale manufacturing advancements. Full article

Lithography serves as a fundamental process in the realms of microfabrication and nanotechnology, facilitating the transfer of intricate patterns onto a substrate, typically in the form of a wafer or a flat surface. Grayscale lithography (GSL) is highly valued in precision manufacturing and research endeavors because of its unique capacity to create intricate and customizable patterns with varying depths and intensities. Unlike traditional binary lithography, which produces discrete on/off features, GSL offers a spectrum of exposure levels. This enables the production of complex microstructures, diffractive optical elements, 3D micro-optics, and other nanoscale designs with smooth gradients and intricate surface profiles. GSL plays a crucial role in sectors such as microelectronics, micro-optics, MEMS/NEMS manufacturing, and photonics, where precise control over feature depth, shape, and intensity is critical for achieving advanced functionality. Its versatility and capacity to generate tailored structures make GSL an indispensable tool in various cutting-edge applications. This review will delve into several lithographic techniques, with a particular emphasis on masked and maskless GSL methods. As these technologies continue to evolve, the future of 3D micro- and nanostructure manufacturing will undoubtedly assume even greater significance in various applications. Full article

Grayscale lithography (GSL) is an alternative approach to the standard binary lithography in MEMS fabrication, enabling the fabrication of complicated, arbitrary 3D structures on a wafer without the need for multiple masks and exposure steps. Despite its advantages, GSL’s effectiveness is highly dependent on controlled lab conditions, equipment consistency, and finely tuned photoresist (PR) exposure and etching processes. This works presents a thorough investigation of the challenges of GSL for silicon (Si) wafers and presents a detailed approach on how to minimize fabrication inaccuracies, aiming to replicate the intended design as closely as possible. Utilizing a maskless laser writer, all aspects of the GSL are analyzed, from photoresist exposure parameters to Si etching conditions. A practical application of GSL is demonstrated in the fabrication of 4-μm-deep $f$#/1 Si Fresnel lenses for long-wave infrared (LWIR) imaging (8–12 μm). The surface topography of a Fresnel lens is a good case to apply GSL, as it has varying shapes and size features that need to be preserved. The final fabricated lens profiles show a good match with the initial design, and demonstrate successful etching of coarse and fine features, and demonstrative images taken with an LWIR camera. Full article

As an alternative to SU-8 soft lithography, a new silicon mold process of fabricating PDMS microchannel chips was proposed. A picosecond laser is used to cut through a 550 μm thick silicon wafer and generate the original microchannel pattern with a 50 μm minimum feature size. This single-crystal silicon pattern, with the edge debris caused by laser cutting being trimmed off by a KOH solution and with the protection field oxide layer being removed by BOE afterwards, firmly resided on a glass substrate through the anodic bonding technique. Four-inch wafers with microchannel patterns as the PDMS mold cores were successfully bonded on Pyrex 7740 or Eagle XG glass substrates for the follow-up PDMS molding/demolding process. This new maskless process does not need a photolithography facility, but the laser cutting service must be provided by professional off-campus companies. One PDMS microchannel chip for particle separation was shown as an example of what can be achieved when using this new process. Full article

LED devices are increasingly gaining importance in lithography approaches due to the fact that they can be used flexibly for mask-less patterning. In this study, we briefly report on developments in mask-free lithography approaches based on nano-LED devices and summarize our current achievements in the different building blocks needed for its application. Individually addressable nano-LED structures can form the basis for an unprecedented fast and flexible patterning, on demand, in photo-chemically sensitive films. We introduce a driving scheme for nano-LEDs in arrays serving for a singularly addressable approach. Furthermore, we discuss the challenges facing nano-LED fabrication and possibilities to improve their performance. Additionally, we introduce LED structures based on a hybrid nanocrystal/nano-LED approach. Lastly, we provide an outlook how this approach could further develop for next generation lithography systems. This technique has a huge potential to revolutionize the field and to contribute significantly to energy and resources saving device nanomanufacturing. Full article

In this research, a novel approach is presented to enhance the precision of open-type optical linear encoders, focusing on reducing subdivisional errors (SDEs). Optical linear encoders are crucial in high-precision machinery. The overall error in optical linear encoders encompasses baseline error, SDE, and position noise. This study concentrates on mitigating SDEs, which are recurrent errors within each pitch period and arise from various contributing factors. A novel method is introduced to improve the quality of sinusoidal signals in open-type optical linear encoders by incorporating specially designed angle shift patterns on the main scale. The proposed method effectively suppresses the third order harmonics, resulting in enhanced accuracy without significant increases in production costs. Experimental results indicate a substantial reduction in SDEs compared to traditional methods, emphasizing the potential for cost-effective, high-precision optical linear encoders. This paper also discusses the correlation between harmonic suppression and SDE reduction, emphasizing the significance of this method in achieving higher resolutions in optical linear encoders. Full article

Two-dimensional (2D) piezoelectric semiconductor materials are garnering significant attention in applications such as intelligent sensing and energy harvesting due to their exceptional physical and chemical properties. Among these, molybdenum disulfide (MoS₂), a 2D wide-bandgap semiconductor, exhibits piezoelectricity in odd-layered structures due to the absence of an inversion symmetry center. In this study, we present a straightforward chemical vapor deposition (CVD) technique to synthesize monolayer MoS₂ on a Si/SiO₂ substrate, achieving a lateral size of approximately 50 µm. Second-harmonic generation (SHG) characterization confirms the non-centrosymmetric crystal structure of the wide-bandgap MoS₂, indicative of its piezoelectric properties. We successfully transferred the triangular MoS₂ to a polyethylene terephthalate (PET) flexible substrate using a wet-transfer method and developed a wide-bandgap MoS₂-based micro-displacement sensor employing maskless lithography and hot evaporation techniques. Our testing revealed a piezoelectric response current of 5.12 nA in the sensor under a strain of 0.003% along the armchair direction of the monolayer MoS₂. Furthermore, the sensor exhibited a near-linear relationship between the piezoelectric response current and the strain within a displacement range of 40–100 µm, with a calculated response sensitivity of 1.154 µA/%. This research introduces a novel micro-displacement sensor, offering potential for advanced surface texture sensing in various applications. Full article

Two-photon lithography (TPL) plays a vital role in microstructure fabrication due to its high processing accuracy and maskless characteristics. To optimize the manufacturing quality deteriorated by the defocus of the substrate, an autofocus approach based on improved differential confocal microscopy (IDCM) is proposed in this paper. Through analyzing the intensity response signals from two detectors with symmetrical axial offset, the defocus amount is measured and compensated for with high precision and noise immunity to stabilize the substrate. The verification experiments on the coverslip reported a detection sensitivity of 5 nm, a repetitive measurement accuracy of less than 15 nm, and a focusing accuracy reaching around 5 nm. The consistency between simulation and characterization demonstrated the effectiveness and superior performance of the autofocus system for the high production quality of the metalens array. The proposed autofocus method shows promise for further application to the fabrication of complex structures on various substrates. Full article